Major turn-on to both, as long as it's not too much and in good taste. Some folks take it to the extreme and it just ends up looking weird.
Pierced nipples drive me crazy, in a good way. Star wars tattoos (of course) on a woman also drive me crazy. But it's all good; dragons, celtic knots, stars, tribal...as long as it's done well.
I have always been attracted by it. It's always been part of my lifestyle. A woman with no tats or piercings looks like a blank canvas to me...which isn't necessarily a bad thing, especially if she's sexy to begin with...I am an artist first, so it appeals to me when I see a woman with cool art on her body. It's just....sexy.
Too much of it ends up looking odd. I've seen more metal on a woman's face than a modern car, and I think she's compensating for something or obsessed with it, or whatever...it's distracting. Same with too much ink...and tthat stuff is damned expensive...there's other things to spend money on, it seems irresponsible to spend that much cash on just ink, y'know?
My wife and I both have a few tats and piercings here and there. But really, we have responsibilities that suck up most of our money.